The present invention generally relates to a field of controlled-release delivery systems for macromolecules, particularly those for nucleic acids and gene therapy. More specifically, the present invention relates to nanocapsules having a diameter of less than about 50 nanometers, in which a bioactive component is located in a core of the nanocapsule, and to methods of forming these nanocapsules.
Over the past several decades, active and extensive research into the use of nanoparticles in the delivery of bioactive agents has generated a number of approaches in the preparation of nanoparticles. These approaches typically include the use of heat, high pressure homogenization, or high intensity ultrasound sonication to prepare nanoparticles having a diameter of more than 100 nanometers, or high amounts of solvents or oils, cytotoxic chemicals, such as cross-linking agents, adjuvants, catalysts or any combination of any of these, to prepare nanoparticles having a diameter of less than 100 nanometers. Furthermore, these approaches are challenging due to a number of variables.
For example, when organic solvents are included in the manufacturing process for nanoparticles, the organic solvent may denature the bioactive agent which reduces most, if not all, efficacy of the bioactive agent. In fact, denaturation of the bioactive agent may promote a toxic response upon administration of the nanoparticle, to a human subject, for example.
In addition, when an organic solvent is used to prepare nanoparticles, the organic solvent or solvent soluble polymer may undergo degradation to form a low pH environment that destroys the efficacy of the bioactive agent. Therefore, organic solvents may generally denature the bioactive agent during or after preparation of a nanoparticle.
As a result, organic solvents are typically removed during the manufacturing process of nanoparticles. However, inclusion of one or more organic solvent removal techniques generally increases the costs and complexity of forming nanoparticles.
The incorporation of high pressure homogenization or high intensity ultrasound sonication to prepare nanoparticles typically results in entangling or embedding the bioactive agent in a polymeric matrix of the nanoparticle. Entangling or embedding the bioactive agent in the polymeric matrix may also denature the bioactive agent to thereby reduce the efficacy of the bioactive agent.
Entangling or embedding the bioactive agent in the polymeric matrix of the nanoparticle may also reduce the efficacy of the bioactive agent by permitting premature release of the bioactive agent prior to reaching a target cell. Premature release of the bioactive agent typically promotes cytotoxicity or cell death during administration of the nanoparticle.
Furthermore, nanoparticles that reach the target cell are typically transported into the target cell via endosomal regulated pathways that results in lysosomal degradation of the bioactive agent and the nanoparticle. Therefore, functional activity of the bioactive agent inside the target cell may not occur since the bioactive agent and the nanoparticle undergoes degradation. As used herein, the term xe2x80x9cfunctional activityxe2x80x9d refers to an ability of a bioactive agent to function within a target cell for purposes of providing a therapeutic effect on the target cell.
Additionally, high pressure homogenization or high intensity ultrasound sonication techniques often require complex and expensive equipment that generally increases costs in preparing nanoparticles. Therefore, an urgent need exists to prepare nanoparticles without the use of cytotoxic chemicals like organic solvents or the use of complex and expensive equipment. Furthermore, an urgent need exists to prepare nanoparticles that do not entangle nor embed the bioactive agent in the nanoparticle so that cytotoxic responses are minimized. Additionally, an urgent need exists to develop a nanoparticle that may be transported into a target cell where the bioactive agent is released to accomplish therapeutic delivery of the bioactive agent.
The present invention generally relates to nanocapsules and methods of preparing these nanocapsules. The present invention includes a method of forming a surfactant micelle and dispersing the surfactant micelle into an aqueous composition having a hydrophilic polymer to form a stabilized dispersion of surfactant micelles. The method further includes mechanically forming droplets of the stabilized dispersion of surfactant micelles, precipitating the hydrophilic polymer to form precipitated nanocapsules, incubating the nanocapsules to reduce a diameter of the nanocapsules, and filtering or centrifuging the nanocapsules.